GEEN 1300
Introduction to Engineering Computing
Fall 2009
Lab Workshop #8
Purpose:




develop VBA procedures to manipulate ranges of cells on the spreadsheet
learn different ways to run a VBA Sub from Excel
write a series of short procedures to manipulate arrays in VBA
create an array function that returns more than a single value to the spreadsheet
1. Launch Excel 2007 and go through the typical setup procedure for VBA program development:
 display the Developer tab
 set Macro security to enable all macros
 set Require Variable Declaration in the Visual Basic Editor
2. Enter the following numbers as shown on the spreadsheet to the
right.
The first VBA procedure you will develop has the purpose of
condensing the range of cells with entries to remove the blank
cells. This is a very common task, and one that comes up again
and again as a candidate for a VBA procedure.
First, to preserve your original entries, copy cells B2:B11 to
D2:D11 and select the latter range of cells.
Launch the VBE ( Alt-F11 ) and insert a module into the project associated with your Excel workbook.
Write and test the following short VBA Sub.
This demonstrates how you can determine from VBA how many rows are in an arbitrary selection of
cells. It is useful for VBA code that must operate on a selection that might change from one execution
to the next.
Next, we need to know the code required to delete a cell and shift the cells below it upward. The
easiest way to do this is to record a macro while performing the operation on the spreadsheet. Enter
an arbitrary number in cell F2. Select that cell. Record a macro for the following procedure
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right-click
delete
shift cells up
OK
Examine the VBA code created (in a separate module). Write in below what is the single VBA
statement that accomplishes the delete.
_______________________________________________________________________________
Return to the first module and modify the Sub as shown below.
In the space below, draw a flowchart to represent the code above (insert tab, shapes->flowchart).
<< space on worksheet >>
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Single-step the Sub with F8. Keep your eye on the value of the RowCount variable. Also, check the
status of the spreadsheet frequently with Alt-F11.
Note the statement
When a cell is deleted and the ones below it are shifted up, then the original range of cells is shrunk
by one. That implies then that the number of rows that need to be searched is reduced by one.
Continue the execution until the Sub is complete.
Return to the spreadsheet and observe the result. Then copy the cells B2:B11 to D2:D11 again and
select cells D2:D11.
3. Running a Sub (macro) from Excel
A simple way to run a Sub from Excel is from the Macro menu. This can be done by
clicking the Macros button on the Developer tab of the ribbon
or via the shortcut key combination Alt-F8. Try both to see that you can access the
Macro window. The Condense macro should appear there.
With D2:D11 selected, click the Run button and the macro should run. Copy the cells B2:B11 to
D2:D11 again.
Another, fancier way to set up for running a macro is to place a custom button on the
worksheet. To do this, click the Insert button on the Developer tab. Click on the Button
image in the Form Controls group.
Move the mouse cursor to an
empty region of the spreadsheet. It should appear as a plus.
Drag out a button of
reasonable size.
An Assign Macro window should appear (it may cover up the
button for now). Select the Customize macro from the list, as shown to the right.
Click OK at the bottom of the window and the Condense macro has been linked to the button. Next,
"scrub across" the button with your mouse and change the name on the button to "Condense." Click
away from the button, and it should appear like
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Make sure that D2:D11 are selected and these cells contain the same pattern as B2:B11. Then click
the Condense button and the macro should run. Pretty cool!
Let's try another way by adding a command button to the QuickLaunch toolbar. Click the Office
Button, Excel Options and Customize. You should see
In the Choose commands from: field, drop the list
down and select Macros.
When the Macros list appears, click on the Condense
item, and then the Add button to the right.
Click OK at the bottom of the window. A small
button appears at the right of the toolbar at the
upper left of the display.
The new "Condense" command button is at the right.
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If you let your mouse hover on the button a "Condense" tooltip should appear. Very nice. Set the
D2:D11 range up for the macro again and click the command button on the QuickLaunch toolbar.
So, you might consider what's the difference between a button on the spreadsheet and one on the
QuickLaunch toolbar. Consider the following:
1) The button on the spreadsheet goes out of view when you move to another region of the
spreadsheet; whereas the QuickLaunch command button is always visible.
2) The Condense button on the QuickLaunch toolbar does not go away when the current workbook
file is closed. And, if you attempt to click the button when this workbook is closed, you will get
an error message.
These observations lead to the following strategy:

Use buttons on the worksheet for macros that are particular to this workbook.

Use command buttons on the QuickLaunch toolbar for generic macros that are stored in the
Personal Macro workbook.
So, how to remove that button from the QuickLaunch toolbar.
Go back through the Office Button, Excel Options and
Customize. Select the Condense item on the right and click
Remove. Then click OK.
The command button should no longer appear on the
QuickLaunch toolbar.
Save your workbook at Lab08a.xlsm and close it out.
4. Open a new workbook and enter the numbers as shown below.
Since Excel is used frequently to manage numbers in rectangular arrays like this, it is useful to know
how to access and manipulate arrays in VBA too. There are two ways to access or transfer an array
of values to VBA:


as an argument to a Function
by using a Range object in either a Sub or a Function
First, you will develop a Function that returns the maximum value of in an array of cells which is the
argument to the Function. Switch over to VBA and insert a new module. Enter the following code:
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Option Explicit
Option Base 1
Function MaxVal(DataArray)
Dim NumRows As Integer, NumCols As Integer
Dim i As Integer, j As Integer
MaxVal = DataArray(1, 1)
NumRows = DataArray.Rows.Count
NumCols = DataArray.Columns.Count
For i = 1 To NumRows
For j = 1 To NumCols
If DataArray(i, j) > MaxVal Then
MaxVal = DataArray(i, j)
End If
Next j
Next i
End Function
Return to the spreadsheet, and, in cell D7, enter a formula to test the MaxVal function:
=MaxVal(A1:F4)
What result is displayed? _______
Now look back at the VBA code and study the following observations:
a) The Option Base 1 directive is used prior to the Function statement so that array subscripts will
start with 1 and not with 0.
b) The function result, MaxVal, is first set to the 1,1 element of the input array. This is the element in
the upper left-hand corner, in the first row and the first column.
c) The Count property is used to determine the number of rows and columns in the input array, and
the local variables NumRows and NumCols are used to store these values.
d) Two For...Next loops, one nested inside the other, range through all the possible combinations of
row and column index values.
e) The If statement checks to see whether an element of the array is greater than the current value of
MaxVal. If so, it sets MaxVal to this element.
f) The loops then continue checking values in the array until all are checked.
Create a second function below MaxVal called MinVal that determines the minimum value in the input
array1. Test the function by entering this formula in cell D8:
=MinVal(A1:F4)
What is displayed there? _______
1
You can save some time by copying code from MaxVal to MinVal and then modifying it.
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Now, create the function ArrayRange2 shown below that makes use of the two functions, MaxVal and
MinVal, that you have already created.
Function ArrayRange(DataArray)
ArrayRange = MaxVal(DataArray) - MinVal(DataArray)
End Function
Enter this formula in cell D9 back on the spreadsheet:
=ArrayRange(A1:F4)
What value is displayed there? _________
If you are executing a Sub directly from Excel, there are no input arguments [it looks like Sub Name()].
You must then use another method to transfer a set of cells into an array in VBA. Add the code below
to your module to illustrate one way to do this.
Sub ArrayCalcs()
Dim DataArray As Object
Set DataArray = Range("A1:F4")
MsgBox ArrayRange(DataArray)
End Sub
An assignment of an object
requires the Set keyword.
Run this Sub and see that the message box displays the correct result. Save your workbook at
Lab08b.xlsm and close it out.
5. It is possible for a function to return more than one value to the spreadsheet. This type of function is
called an array function. You will now create a simple example of an array function. Open a new
workbook and enter the numbers as shown below:
Let's say we wanted to have a function called PctVal that would display the proportion in % of each of
these numbers to the total of the numbers. This function would have to display its results in 4 cells.
2
If we use the name Range for the function, that will get in the way of VBA's Range object.
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Switch over to VBA, insert a new module, and enter the function shown below:
Option Explicit
Option Base 1
Function PctVal(ValueArray)
Dim NumRows As Integer, i As Integer
Dim Pct() As Single
Dim Sum As Single
NumRows = ValueArray.Rows.Count
ReDim Pct(NumRows)
For i = 1 To NumRows
Sum = Sum + ValueArray(i)
Next i
For i = 1 To NumRows
Pct(i) = ValueArray(i) / Sum * 100
Next i
PctVal = Application.WorksheetFunction.Transpose(Array(Pct))
End Function
Return to the spreadsheet and select the cells B1:B4, and enter the formula as shown in the figure
below.
Since this is an array formula, you must enter it with Ctrl-Shift-Enter. The column B cells should then
show the percentage proportions of the values in the A column. Adjust the display to 1 decimal place.
What four values are displayed?
________
________
________
________
Change one of the values in cells A1:A4 and note that the function updates automatically.
Now, a few comments about the Function PctVal code:
a) The Dim Pct() As Single statement sets up a local variable as an array, but without specifying the
dimensions of the array yet. This is called a "dynamic" array. Later in the code, after the number
of rows in the input array has been determined (NumRows), the Pct array is dimensioned to that
number using the ReDim statement.
b) The sum of the elements in the input array is accumulated in the Sum variable using a For...Next
loop. This sum is needed for the following For...Next loop where the percentages are computed.
c) Finally, the percentages are formed into a "variant array" that can be assigned to the name of the
function, PctVal. The Array function is used for this, but, if only the Array function were used, the
result would appear in a row of cells. Since we want the result to appear in a column of cells, we
use Excel's Transpose function to reorder the row into a column.
Save this workbook as Lab08c.xlsm and close it out.
Leave Excel and return to WindowsLog out.
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End of Lab Workshop #8
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